The invention concerns a method of winding webs of material, especially webs of paper or cardboard, on cores, whereby the web is wound on cores in a bed created by two drums and the full reels are ejected from the bed above one drum by an arm that swings around the other.
The known reel-ejection and core-insertion mechanisms employed in drum-type winders change reels by ejecting the full reel from the bed and inserting a fresh core. A generic method and a drum-type winder is known from German Patent No. 3 151 256. It has a reel-ejection mechanism that swings around one drum and toward the bed and has an arm with an ejection surface that extends more or less radially in relation to the drum. The reel-ejection mechanism and the core-insertion mechanism are mechanically separate, and each swings separately toward the bed.
German Patent No. 2 948 877 describes a drum-type winder with a combination ejection-and-insertion mechanism. It has a reel-ejection arm and a core-insertion structure. The ejection surface on the arm terminates at a distance from the drum, and the core-insertion structure releases the core in the space between the ejection surface and the drum. The ejection-and-insertion mechanism consists of the arm and of tensioning tongs. Both the arm and the tongs are secured to a common lever and can accordingly swing together around one drum and into the bed. The ejection surface on the arm extends more or less radially in relation to the drum and terminates at a distance from it that is longer than the drum's diameter, allowing the tongs, which are integrated into the arm, to intercept the core in the space between the ejection surface and the drum and insert it in the bed.
Another drum-type winder of the same genus is described in German No. OS 3 527 377. The ejection-and-insertion mechanism in this winder also has a retainer between the tongs' jaws that allows the core to be lowered without being rotated onto the drums once it has swung over the bed.
The drawback to all these known drum-type winders is that the arm can only eject reels that have a minimum diameter because they must be forced up as far as the apical line of the first drum. In combination ejection-and-insertion mechanisms, the minimum diameter is more than twice as long as the distance between the bottom end of the ejection surface on the arm and the drum around which the core swings that is necessary to the function of the insertion mechanism. Furthermore, if an attempt is made to eject a reel with too short a diameter, the reel-insertion mechanism can always be forced against the reel and damaged.
It can occur in practice for many reasons that, just after winding has begun, a complete set of reels is to be ejected and removed from the bed. If some of the reels are not yet at their minimum diameter, they must be lifted out of the bed manually. Since the reels will be fairly heavy even by then, this situation constitutes a source of considerable stress on the operators.